Decabromodiphenyl oxide (deca) and decabromodiphenylethane (deca-DPE) are commercially available materials widely used to flame retard various polymer resin systems. The structure of these materials is as follows:

One of the advantages of using deca and deca-DPE in polymer resins that are difficult to flame retard, such as high-impact polystyrene (HIPS) and polyolefins, is that the materials have a very high (82-83%) bromine content. This allows a lower load level in the overall formulation, which in turn serves to minimize any negative effects of the flame retardant on the mechanical properties of the polymer.
Despite the commercial success of deca, there remains significant interest in developing alternative halogenated flame retardant materials that are higher molecular weight oligomers or polymers. Such oligomers or polymers may provide improved properties, such as providing non-blooming formulations, or better mechanical properties. For example, these types of material tend to become entangled in the base resin polymer matrix, depending on the compatibility between the resin and the flame retardant, and hence should show fewer tendencies to bloom. This would in general give a more inherently “environmentally friendly” material, as it would not be as easily transferred to the surrounding environment.
There are a number of commercially available flame retardant materials that can be considered oligomers or polymers of halogenated aryl monomers. Examples of these monomers include tetrabromobisphenol A (TBBPA) and dibromostyrene (DBS), which have the following structures:

Commercially, TBBPA and DBS are typically not used in their monomeric form, but are converted into an oligomeric or polymeric species. One class of oligomers is the brominated carbonate oligomers based on TBBPA. These are commercially available from Chemtura Corporation (examples include Great Lakes BC-52™, Great Lakes BC-52HP™, and Great Lakes BC-58™) and by Teijin Chemical (FireGuard 7500 and FireGuard 8500). These products are used primarily as flame retardants for polycarbonate and polyesters.
Brominated epoxy oligomers, based on condensation of TBBPA and epichlorohydrin, are commercially available and sold by Dainippon Ink and Chemicals under the Epiclon® series, and also by ICL Industrial Products (examples are F-2016 and F-2100) and other suppliers. The brominated epoxy oligomers find use as flame retardants for various thermoplastics both alone and in blends with other flame retardants.
Another class of brominated polymeric flame retardants based on TBBPA is exemplified by Teijin FG-3000, a copolymer of TBBPA and 1,2-dibromoethane. This aralkyl ether finds use in ABS and other styrenic polymers. Alternative end-groups, such as aryl or methoxy, on this polymer are also known as exemplified by materials described in U.S. Pat. No. 4,258,175 and U.S. Pat. No. 5,530,044. The non-reactive end-groups are claimed to improve the thermal stability of the flame retardant.
TBBPA is also converted into many other different types of epoxy resin copolymer oligomers by chain-extension reactions with other difunctional epoxy resin compounds, for example, by reaction with the diglycidylether of bisphenol A. Typical examples of these types of epoxy resin products are D.E.R.™ 539 by the Dow Chemical Company, or Epon™ 828 by Hexion Corporation. These products are used mainly in the manufacture of printed circuit boards.
DBS is made for captive use by Chemtura Corporation and is sold as several different polymeric species (Great Lakes PDBS-80™, Great Lakes PBS-64HW™, and Firemaster CP44-HF™) to make poly(bromostyrene) type flame retardants. These materials represent homopolymers or copolymers. Additionally, similar brominated polystyrene type flame retardants are commercially available from Albemarle Chemical Corporation (Saytex® HP-3010, Saytex® HP-7010, and PyroChek 68PB). All these polymeric products are used to flame retard thermoplastics such as polyamides and polyesters.
In our U.S. Patent Application Publication No. 2008/0269416, we have proposed a series of flame retardant materials that are based on halogenated aryl ether oligomers comprising the following repeating monomeric units:
wherein R is hydrogen or alkyl, especially C1 to C4 alkyl, Hal is halogen, normally bromine, m is at least 1, n is 0 to 3 and x is at least 2, such as 3 to 100,000. The oligomer precursors are produced by oligomerization of a hydroxyhaloaryl material, such as bromophenol, or by reaction of a dihalo aryl material, such as dibromobenzene, with a dihydroxyaryl material, such as resorcinol, using an ether synthesis, such as the Ullmann ether synthesis. Bromination of the resulting oligomers produces materials that are halogenated to a higher level than other currently available oligomeric flame retardants and that provide superior mechanical properties when combined with resins such as HIPS and polyolefins as well as engineering thermoplastics such as polyamides and polyesters. It is also found that these aryl ether oligomers, even at lower levels of halogenation, give formulations with acceptable mechanical properties.
All of the polymeric or oligomeric flame retardant materials discussed above are based on aromatic bromine, which has a higher thermal stability than an aliphatic bromine material. For this reason, one of the disadvantages of existing halogenated aromatic polymeric flame retardants is that they are only effective in reducing the flammability of the host resin material at relatively high temperatures. For certain host resin materials, such as polyolefins, it would be desirable to have a flame retardant that exhibits the physical properties of brominated polymers but has a flame retardant mechanism that is effective at lower temperatures than conventional halogenated aromatic polymers.
According to the present invention, it has now been found that by reacting a polyhaloalkene with a polyhydroxyaryl compound, or more preferably a halogenated polyhydroxyaryl compound, such as tetrabromobisphenol A (TBBPA), it is possible to produce an arylalkenyl ether oligomer/polymer. This oligomer contains olefinic unsaturation and so, on halogenation, especially bromination, it produces a halogenated arylalkyl ether oligomer/polymer having both aliphatic and aromatic halide groups. As a result the halogenated product combines the advantageous physical and high temperature flame retardant properties of conventional halogenated aromatic polymers with the lower temperature flame retardant properties of halogenated aliphatic molecules.
U.S. Pat. No. 4,079,034 discloses a flame retardant additive comprising an aromatic polyester of an aromatic dicarboxylic acid and a halogenated bisphenol having the formula:
wherein E is a divalent alkylene, haloalkylene, cycloalkylene, halocycloalkylene, arylene, haloarylene, —O—, —S—, —SO—, —SO2—, —SO3—, —CO—,
or R5N<; R1 is alkyl, haloalkyl, aryl, haloaryl, alkylaryl, haloalkylaryl, arylalkyl, haloarylalkyl, cycloalkyl, or halocycloalkyl; R4 and R5 are independently selected from hydrogen, R1 and OR1; m is an integer from 0 to the number of replaceable hydrogen atoms on E; a, b, c and d are 0 to 4; and a+b is 1 to 4 and c+d is 1 to 4.